Is your sending domain on a blacklist?
Enter a domain or IP. Four blocklists are queried live over DNS, and each answer is labelled listed, clear or no answer.
- Four blocklists
- Live DNS lookup
- No email required
The short answer
- A DNS blocklist (DNSBL) is a DNS zone that answers with a 127.0.0.x address when an IP or domain is listed, and with NXDOMAIN when it's clear.
- This checker queries the Spamhaus DBL for the domain, then Spamhaus ZEN, SpamCop and Barracuda for up to six of the domain's server IPs.
- Spamhaus refuses public resolvers with 127.255.255.x codes, so those results show as no answer, never as listed.
- A clear result on every list means the lists aren't your problem. Look at authentication, volume and complaint rates next.
How each lookup works
Blocklists publish their data as DNS. To check an IP, you reverse its four numbers and ask for an A record under the list's zone. So 203.0.113.7 on SpamCop becomes a lookup of 7.113.0.203.bl.spamcop.net. A domain check on the Spamhaus DBL asks for yourdomain.com.dbl.spamhaus.org.
Your browser sends each query to Cloudflare's DNS-over-HTTPS resolver, with Google Public DNS as the fallback. For a domain, the checker first finds its A records and the A records of up to three MX hosts, then checks up to six IPs. Each answer is read by this rule:
- Clear: the list answers NXDOMAIN, meaning no entry exists.
- Listed: an answer in 127.0.0.x for the IP lists, or 127.0.1.x for the Spamhaus DBL.
- No answer: a 127.255.255.x refusal code, a DNS error or a timeout.
The four lists this checker queries
| List | What it lists | Query zone | Public-resolver behaviour |
|---|---|---|---|
| Spamhaus DBL | Domains seen in spam | dbl.spamhaus.org | Refuses with 127.255.255.x |
| Spamhaus ZEN | IPs: spam sources, exploits, end-user ranges | zen.spamhaus.org | Refuses with 127.255.255.x |
| SpamCop | IPs reported by SpamCop users | bl.spamcop.net | Answers normally |
| Barracuda | IPs with poor sending reputation | b.barracudacentral.org | Answers normally |
Resolver behaviour checked with live DNS-over-HTTPS queries to cloudflare-dns.com, September 2026.
Three inputs and what you'd see
127.0.0.2. DNS blocklists keep this address listed as a standard test entry. SpamCop and Barracuda both answer 127.0.0.2, so they show Listed. Spamhaus ZEN answers 127.255.255.254 through Cloudflare, so it shows No answer.
A clean IP such as 8.1.1.1. SpamCop and Barracuda answer NXDOMAIN and show Clear. Spamhaus again shows No answer, and you'd confirm it at check.spamhaus.org.
A domain on Google Workspace. You'll get the DBL row for the domain, then rows for its web server IPs and Google's MX IPs. Your sending mail leaves from Google's servers, so a clear result there mostly tells you about the domain's own reputation.
Complaints and bounces come before listings
Questions
- How do I check if my domain is blacklisted?
- Query each blocklist over DNS. The checker above looks up your domain on the Spamhaus DBL, then checks the domain's web and mail server IPs on Spamhaus ZEN, SpamCop and Barracuda, all from your browser.
- Why does Spamhaus show no answer?
- Spamhaus refuses queries that arrive through large public resolvers and replies with a 127.255.255.x code. The checker reports that as no answer, never as a listing. Check Spamhaus directly at check.spamhaus.org for a definite result.
- How do I get removed from a blacklist?
- Fix the cause first, then use the list's own removal page. SpamCop listings expire on their own about 24 hours after reports stop. Barracuda and Spamhaus each run a removal request form on their sites.
- Does a blacklist listing stop my cold email?
- It can. Receivers that use the list reject or junk mail from the listed IP or domain. Gmail and Microsoft run their own reputation systems too, so watch bounce and complaint rates as closely as the lists.
Keep your domains off the lists
SalesCrew enforces per-mailbox and per-domain daily caps, and turns every bounce and complaint into a suppression.